vozaday

I would say power is a big part. The fuel system is limited on the HPFP. The dual system is what allows the new GT to break the 600hp mark.

Yes it has a big part in cleaning valves. No debating that.

Semi

I replaced my plugs last summer at about 80000 km. The plug gap was at- hang onto your seats- .94!!!! I couldn't believe the thing was still running. One of them was seized so I replaced the 2 I had removed and let the dealership deal with it. It was a worthwhile expense because I know they can't pin any plug breakage on me!

I should have taken a picture of the stacked feeler gauges in that Grand Canyon of a plug gap. I may have, and should look back to see if I in fact did!

Anyway, regular plug changes are a must. These engines work pretty hard and I do pull a trailer. So with the effort I get out of this little engine I'm happy to give it a set of plugs every so often!

woody3

Most modern day COP ignition systems will work just fine with a wider than standard plug gap. The problem arises when a bit of steam causes the effective compression ratio to rise well above normal operation.

itguy08

I think Toyota uses a similar system on some of their DI engines. I think the explanation from them was it was also to improve efficiency at some point in the rev range.

Here's an interesting read on Toyota's system:
http://wardsauto.com/news-amp-analys...ofold-strategy

It should also keep the deposits off the valves, something a can won't do (the VW/Audi/BMW folks are finding that out).

papa tiger

The Direct Injection can only inject so much fuel, at that point the port injector can make up for additional amounts for torque needs/answers. To put that in perspective the Direct fuel will get to 2.7Mpg and the port injection will put it down to .5 MPG.

woody3

Sorry, but port injection cannot be used in conjunction with DFI when the effective CR is near or equal to the actual CR.



With WOT and a CR of ~12:1 an extremely rich mixture at the onset of the compression stroke would be needed to prevent detonation before reaching TDC, leaving no "room" for DFI.


DFI, injecting fuel ONLY as the piston approaches TDC, effectively cools the compressed air in the combustion chamber as it reaches TDC, therefore allowing a higher than otherwise CR.

papa tiger

U have that all wrong, with the Ford Direct injection multi injects per sequence of piston intake/compression cycle. The GT's with both systems on them, the port injection is to make up for the lack of fuel amount capability of the DI system.

woody3

With a high compression (~10:1) SFI engine at WOT when the intake valve closes the mixture MUST be rich enough to prevent detonation prior to spark ignition.


What do you suppose would happen if you lowered the fuel allotment prior to intake valve closing?


That's why the SFI sect,ion of a DFI engine CANNOT do a partial fill.


Just as long as the effective CR isn't "near" the actual CR then both SFI & DFI can be used. Probably up to ~10:1 for a 12:1 DFI engine.


http://wardsauto.com/news-amp-analys...ofold-strategy

Abraham5G

I just changed mine for the first time at 21,000 miles on my '14 ecoboost. Original gaps ranged from .032 to. 034. I gapped the new ones to .030. The old ones look pretty bad: